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' F. B. MACLABEN.

ELECTRIC GUN. I APPLICATION FILED MAR. 18. 1916. 1,884,769. PatentedJuly 19,1921.

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F. B.. 'MACLAREIL ELECTRIC GUNl V APPLICATION FlLE MAR. 16, 1916,

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' @nvm/woz I @MS04/Mur! Patented July 19, 1921.,

. F. B. MAcLAREN.

ELECTRIC GUN.

loN FILED MAR l1s 9| APPLlcAT .,1 s. 1,384,769. Patented July 19, 1921.

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eJen'c/ 7572:: anni UNITED STATES lEaEiJ'Emci: B. moLAEEN-,Q JERSEYcriar, NEW JERSEY. AssIvGNoE To' ELEcfnriIc" or rm-LADELrHiA,PENNsjYLvANrA, A conronA'rzoN or GUN coEPoRATioN,

DELAWARE.

T o all whom t may` concern:

Be it known that I, FREDERICK" B. MAC- .LAREN, a citizen of the UnitedStates, resid.l ing at/Jersey City, countyfof Hudson, andv State of NewJersey, have invented certain new and useful Improvements in ElectricGuns; and I do hereby declare the following to be a full, clear, andexact description.,

of the invention, such as will enable others skilled in thev art towhich itv appertains', to

make and use the same.

The invention .relatesto electric guns, and

has for one obj ect to provide a novel method of discharging orpropelling projectiles, which consists in generating traveling mag-.netic fields, annular in form, propagatedin the direction of thedesired line'of flight of the projectile, by means of polyphase electriccurrent developed and ldelivered by a generator ,so constructed as to becapable of storing up energy, as in a heavy rotating mass and deliveringthe same, when desired,

in the forni of current of high frequency Y prising a barrelsurroundedby a series of the gun muzzle at .the attained velocity.'

annular coils so disposed and arranged that,

when they are connected to the leads'fromA the generator, they willproduce -a series of traveling. annular magnetic fields progressingsuccessively from the breech to themuz.- zle'of the gun, so that when asuitable projectile is placed in the breech, said projectile will besubject to the effect of current',

induced in it by said traveling magnetic fields andwill be movedthroughjthe bore of the gun barrel toward the\muz-zle,'wi'tl1 anincreasing velocity, which ultimately approximates that of the travelingmagnetic fields', and vsaid projectile is discharged from These andvother objects and novel fea` tures of the invention will appear from'theannexed descriptiomin connection `with vthe accompanying drawings, invvlilch:A 'l n' z 'inodeiand place of use;` 1

As illustrated in Figs. 1, 4^ and'5,the gun barrel preferably consistsof--an inner tubu. larimember" 1 provided 'with a-clear unobstructedbore and open l,at both ends which QStaitially PATENT 5 OFFICE'.

-EEECTEIG grim;y

, specification of Leaersimen. Patented July 19, 1921, vApplicationfleli March 16, 1916. Serial No. 84,674.A v

. Figure 1 is a side elevation of a gun and the means for operating thesame.

Fig. 2 -isa side elevation, partly in section, 01:' a shell orprojectile adapted for use with th gun.. A

' Fig. 3 1s a diagram ofthepower circuits'. y

Fig. 4. is a vertical -transverse section through the gun-taken on theIine'4-4 ,of Fig. 5, with coils omitted.- l

Fig. 5 is a fragmentary longitudinalsection through-the gun taken online 5-5 of Fig. 4.

Fig. 6 is a view similar to that shown inI Fig. 4, illustrating amodiication of the gun structure. v

Fig. 7 is a side-elevation of. ashell or j projectile adapted for usewith ,a gun of the' type shown in Fig. '6. Figs. 8 and 9 "areYrespectivelypa side. andan end4 view of a modified form of projectile,and Fig. 10 isfa. Vdiagrammatic view illustrating one way of changing'pole' pitch.

Referring tothe drawings, and more particularly to Fig. 1, A' lindicatesthe barrel offthe gun as a whole, which `in the'type shown is mounted bythe usual form of trun.

nions F upon a swiveledbase B sup orted on a suitable sub-base orfoundation` and is provided withany suitable type ofV re-'l coilmechanism C, traversing mechanism E,

elevating'l mechanism D, and' sighting de vices I. Obviously, any oflthe other usual or Well known types of'mountingand operating mechanismmay be employed to suit the .particular character of "voJ the vgun andits v constitutes theA guidewayflfor the'projectile.V

Thisinner member lis preferably formed of a tube of metal possessinghigh specific resistance to electric currents,I such, forl ex'- ample,as silicon'steel, or, where practicable,

of a non-coiiductingy'material, such as indurated' ber or: a compositematerial possessing vsuliicient strength to withstand the the gun' vis.100' tressesv imposedfupon. it.- Bymaking the.

v sections 10 by means of sleeves and washers 13 of induratedl fiber orother good insulat-l ing medium. The splittingv of the jacket 10 is toprevent short circuit currents from iowing in it.

The annular space between the inner and outer tubular members 1 and -10is subdi-v vided transversely by means of annular partitions 15, whichin turn are provided at intervals with radial generally triangular ribsor fins 16, the partitions and ribs, 15 and 16, being preferably rigidlyconnected or formed integrally with the outer sections 10 of the jacket.

Arranged within the cellular structure formed by theinner tube 1 and theouter jacket 10 is a series of annular coils c', '02, c3., arranged issuccessive groups'andexten'ding from the breech to the' muzzle of thegun, each of said coils being so formed as to con form to the .annularspace defined between the vertical wall of an adjacent partition 15 andthe rearwardly inclined edges 4of the.

ribs 16 so thatV the partitions ,15 and the strengthening ribs 16 serveto take up thethrust produced in the gun by the passage of va projectilethrough the same and distribute such thrust uniformly throughout the gunbarrel.

It will be understood that the innen tube 1 is rigidly locked to theother parts of the bar- Y. rel structure at the muzzle and breech, or,if

desired, at intermediate points Vvso as to pre vent any independentmovement between the inner tube and the parts of the gun barrel.

The several sets of annular coils c', c2, 03 constitute the' means forygenerating l'in the barrel or bore of the gun, traveling magneticfields, which are propagated -longitudinally of the gun barrel from thebreech toward the muzzle and which, when a projectile of' appropriatematerial is placed in the bore of the gunk at the breech,induce'currents in the projectile, thereby setting up aforce tending tomove the projectile'through the gun to\v ward the muzzle. s

As'illustrated, fthe coils c', c2, c3 are supl plied with current of thealternating threephase type, but obviously current of any otherpolyphase type might be employed by proper selection and arrangement ofthe coils.

Each oup of coils, c', c2, and c3 is connected web the 16ms L', L2 andL3 Aof a threetions being made in accordance with the wir- -ing diagramillustrated in Fig. 3.

The\generator G, designed for high frequency and to deliver very largecurrents for relatively short periods of time, is provided with'a heavyiy wheel G', and is adapted to be coupled up with a steam engine orother prime mover. Theffly. Wheel G' serves as an agency for storing theenergy developed by Athe prime mover and for delivering the storedenergy to the gener-n ator. The necessity forsome energy-storingvmeanswill be apparent when it is remembered that the power supplied by the.

generator is utilized only while the projectile is traveling through thegun barrel and witha gun barrel of the ordinary lengthand Ithe highvelocity imparted to the projectile, each period of time, when power isdemanded of the generator, is but a small fraction of a second. As theamount of power or'energy required'during this *briefv interval of timeis very large, however, the reserve energy stored up in the flyl wheelbecomes available. Y

In order to control'the supply of current from the generator to thecoils o the gun barrel, there is interposed inthe circuit between thegenerator and .the coils a suitable switch S, which in turn iscontrolled by aA push button or other circuit controlling means S',preferably mounted Von the gun barrel and electrically connected withthe switch S. Said switch S may be of any of the well known 'types used`in circuits of this general character.

The projectile P consists of either a solid or hollowk body of metalwhich may be of any `appropriate shape common to' shot or shell.Preferably the projectile ismade of metal having good electricalconductivity.

and suiiicient strength to stand the strains imposed upon it, such assteel, brass, cop, per, aluminum or similar metals. If de- 'sired, theprojectilemay consist of laminated iron asshown at 101, Figs. 8` and 9,associated with insulated copperr conductors 102, the iron portionsacting as. partof the magnetic circuit and the insulated copper asthe-electric circuit for the induced currents. In the preferred form ofthe projectile,A however, the magnetic circuit is not especiallyprovided for, but the good electrical conductivity of the projectile isa desideratum. lThe projectiles, as indicated, may bemade hollow toprovide space fol` an explosive and adetonator, when the projectiletakes the form of a high, explosive, or armor-piercing shell. or toprovide space for powder,ifuse and balls when the projectile is used asa shrapnel. *In order to increase the efiiciency of the projectile as anelement of the electrical system which'efi'ects `ner tubular member 1and .thecoilsc c2v and c3, each of said coils fr", r'and ri beingconnected with the proper lead ofthe poly-'- phase circuit from thegenerator-.so that when the polyphase clrrentflows in theA s id coils,they set vup a rotary field within't e gun barrel which imparts a rotarymotion to the projectile P. It is evident that the gun, as described,when operating to discharge a projectile therethrough, constitutes apolyphase motor of the induction type, of

very high power and relatively small size.

` It is a well known fact that motors of this .vtype generate heatduring their` operation,

and in the present instance, special means is provided for rapidlydissipating the heat generated. This is preferably effected by providingthe outer jacket 1Q of the gun with ribs or fins 2O to increase theconvection and radiation surfaces. In addition to this cooling means,when necessary, the gun may be provided with means for circulatinge,rv acoollng medium, such as oil, around -the colls surrounding the innertube 1, orV

by blowingair around the coils, or by providing the outer'jacket withdouble walls to constitute a water-jacket through which v water or'other cooling medium ymay be forced. In the relatively small gunillusvtrated in the drawings, a` suiiicient cooling effect is producedby the ribs or-fins 20,

` associated with abody of oil confined'V in the spaces between theinner and outer tubular members, not occupied`by`the exciting coilsL theoil serving 'as a medium for conducting^the` heat from the coils to theouter jacket 10,-'whe`re Vit is 'dissipated by the ribs20. "j l ,Insteadofproviding the -gun with the longitudinal coils r', r?, r3, to producea rotary field, to' impart V'the' desired rotaryf' motion to theprojectile, the same result may fbe attained by providing the bore ofthe` t f inner tube 1 with suitable rifling 2, see Fig.

6, which are adapted to be engaged by complementary ribs d, formed onthe projectile d', see Fig. 7 In this ,type of gun, it is nec- ,essaryto prevent any relative rotary motion `between the innerA and cutermembers 1 `and v Ainsulating -tube 3,- which is .located inthe 10 vofthe gun barrel and'to effect this vob ject65V the inner memberlis'securely lockedto'the y outer member v10 by means of a keylt' whichengages mating slots in the outer surface of the vmember 1 and theadjacent peripheral edges of the partitions 15. Preferably, in bothtypes of the gun, as described, the inner -tubular member/.1` is'insulated -from the other .parts o fqth'e barrelby means of aninterposed sheath 'or tube 3 of insulation, and. obviously the key 14shouldbeof -in- 7 5 lsu'lating material or be properly insulated.

the projectile should be fas high as possible,`

and 'as the vvelocity 'of thel projectile cannot f exceed that of thetraveling field, it is, therefore, necessary that the velocity ofthe-traveling fleld should be maintained as high "as practicable. Thevelocityof the traveling field is proportional' to thelpole lpitch andthe frequency of .the inducing current so 95 that by varying orregulating either one or y both 'of thesepfactors, the velocity of thetraveling field may' be correspondingly varied. Referring to Fig. '10,one way of varying the pole pitch is shown. In that figure a. series ofcoils 1O6 is` shown. The first threebeing connected to the polyphasesystem 107 `to form one pole, the following six coils being Aconnectedtothe same system to form a pole of twice the length of the 10 firstpole, and .byrepetitio-n the pole pitch maybe increased indefinitely. J

If the frequency of the currentsin the gun l coils is constant,-the.frequency of \the.cur p rent, induced in theprojectile is highest at 110the breech'I and gradually decreases toward the muzzle asv the velocityvof the projectile increases. It 'is a well known fact that in polyphaseinduction motors of any type, the

forces-acting, on the part carrying the vinduced currents are a maximumfor la certain i frequency of induced currents,` and if the frequency isdescreased, the vforces fall off quickly, and if; increased, the forcesdecrease slowly from sald maximum. In consonance with'this principle,therefore, it is decidedly advantageous` to vmaintain the frequency ofthe inducedfcurrentsin the projectile con- ,V stant, and of such valueas fwill maintain the forces vat a maximum.' This result;can"| 2 5i beapproximated for practicalpurposes by making the velocitybf thetraveling magv netic field comparatively-lowat theb'leec'l gun, an'outer housing,

and gradually increasing toward the muzzle of the gun. rent in the guncoils is constant, the resultl can be attained by varying the polepitch, making it small at the breech and gradually increasingr towardthe muzzle. In addition to this particular mode of varying the velocityof the traveling field, the same result may be effected by increasingthe frequency of the impressed current during the time the projectile istraveling from the breech to the muzzle. of the gun, or by connectingthe successive sets of coils on the gun to generators of differentfrequencies, which vary from a relatively low frequency near the breechand gradually increase to a maximum frequency at the muzzle. Obviouslyeither of these two latter methods may be used in conjunction with thefirst method referred to, to wit, the variation of the pole pitch.

IVhat I .claim is 1. The method of discharging or propellingprojectiles, which consists in generating traveling magnetic fieldspropagated in the direction of the desired flight of the projectile bymeans of polyphase electric current, and subjecting the projectile tothe inductive accelerating influence of said traveling fields.

2. The method of discharging or propelling proj ectiles` which consistsin generating annular traveling magnetic elds propagated in thedirection of the desired flight of the projectile by means of polyphaseelectricA current land Yinterposing the projectile within said annularfields to subject th'e same to the. inductive influence of the latter.

3. The method of shooting projectiles which consists in establishing afield travelin in the direction of flight by means of polyphasevcurrents` and applying the accelerating motor effect of that field to"the projectile to shoot it through theV air.

4. The methodV of shooting projectiles by electricity which consists inproducing a traveling magnetic flux flowing crosswise of the directionof flight and establishing acur- `rent flow in the projectile indirections at right angles to both the flux and Iflight paths andthereby causing the resultant motor effeet to accelerate and shoot theprojectile through the* air.

5. An electric gun for discharging projectiles` comprising a tubularbarrel,projectil'e revolvlng means. a series of annular coilssurrounding the barrel and arranged to produce a traveling magneticfield progressing from the breech to the muzzle of the barrel, and meansfor 4simultaneously supplying 4polyphase electric currents to all ofsaid coils to produce such field.

6. An electric gun for discharging proj ectiles, comprising a barrelhaving V an inner tubular member constituting the bore of the If thefrequency of the cura series of annular coils interposed between theinner and .outer members arranged to produce a traveling magnetic Heldprogressing from the breech to the muzzle of the barrel, and means-forsupplying polyphase electric currents to'j said coils.

. 7 An electric gun for discharging projectiles, comprising a barrel,including a series of annular coils. surrounding the barrel arranged toproduce a traveling magnetic field progressing from the breech to themuzzle of the barrel, a series of coils arranged longitudinally of thebarrel ,to produce a rotary magnetic field within they barrel, and meansfor supplying polyphase'electric current tov the respectlve sets ofcolls.

8. An electric gun for discharging p'rojectiles, comprising a barrelincluding an'inner tubular member of high electrical resistance toeffect a substantially equal distribution of "flux around the tubularmember, a series of annular coils surrounding the tubular mem- .ber andarranged to produce a travelin magnetic xfield pro ressing from thebreec to the muzzle of t e barrel, and means for supplying polyphaseelectric current to said coils.

9. An electric gun for discharging proj ectiles, comprising a barrelincluding an inner tubular member of high electrical resistance, anouter tubular member provided with heat dissipating means, and a seriesof coils interposed between the tubular members and arran ed to produce,Awhen supplied with' polyp ase electric current, a traveling magneticfield progressing from the breech to the muzzle of the barrel.

11. In an electric gun for discharging projectiles, a 'barrel comprisingan inner tubular member, aspaced outer tubular member, an-

nular partitions having ribs extending longitudinally of thel barrel,and annular coils: interposed between said members and bej tween saidpartitions, said coils being ar--" ranged to produce, when supplied withpoly-1 phase electric current, a traveling magnetic field progressingfrom the breech to the muz' I zle of the barrel.

.12.v In an electric gun for discharging projectiles, a barrelcomprising an outer tubular 'member split longitudinally, withinsulation between thej'adjacent edges, an in ner tubular memberpossessing high electrlcal resistance, and a plurality of sets of annutosaid generator to store up energy applied lar coils interposed betweenthe inner and to said generator, and a gun com rising a outer membersand arranged to produce, barrel surrounded by a series o annularWhensupplied with polyphase electric curcoils adapted to besimultaneously connected 5' rent, a traveling magnetic field progressingto said generator to produce a traveling inag- 15 from the breech to themuzzle of the barrel. netic lield progressing from the breech to the 13.An ordnance system propelling projecmuzzle of the gun.l tiles 'at highvelocity, comprising a genera- In testimony whereof I ailix mysignature. tor of polyphase alternating currents of high 1Q frequencyand power, ally Wheel connected FREDERICK B. MAOLAREN.

